Montgomery County Fire Chief Scott Graham says flames broke out in a first floor mechanical shaft just after 11:15 p.m. Thursday, then spread up through the duct work and out of the third floor ventilation system. The fire sent smoke into the Labor and Delivery ward, which prompted personnel to move several patients to a safe area.

Nearly 100 firefighters responded to the scene and were able to knock it down in 20 minutes.

No injuries were reported. The hospital remained open throughout the ordeal.